Apparatus for transmitting and receiving telegraphic messages in code



June 4, 1929. 'DAMM 1.715.904

APPARATUS FOR TRANSMITTING AND RECEIVING TELEGRAPHIC MESSAGES IN CODE Filed Nov. 1927 4 Sheets-Sheet l June 4, 1929. A. ca. DAMM 1,715,904

APPARATUS FOR TRANSMITTING AND RECEIVING TELEGRAPHIC MESSAGES IN CODE Filed Nov. 8, 1927 4 Sheets-Sheet 2 I. I I

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TELEGRAPHIC MESSAGES IN CODE 4 Sheets-Sheet Filed Nov. 1927 June 4, 1929. DAMM APPARATUS FOR TRANSMITTING AND RECEI VING 4 Sheets-Sheet 4 TELEGRAPHIC MESSAGES IN CODE Filed Nov. 8, 1927 Patented June 4, 1929.

UNITED STATES PATENT OFFICE.

ARVID GERHARD DAMM, OF PARIS, FRANCE.

APPARATUS FOR TRANSMITTING AND RECEIVING- TELEGRAIHIC MESSAGES IN CODE.

' Application filed. November 8, 1927, Serial No. 231,824, and in Great Britain November 19, 1926.

The primary object of the invention, which is applicable primarily but not exelusively to radio-telegraphy, is to afford a the original message already transmitted in a disguised shape will serve as key for the same length of message following.

means for safeguarding the secrecy of com- The combination of a preceding part of munication and at the same time to economize electric energy by reducing the length and number of impulses sent through the antenna. The invention adapts itself specially to stations using the Morse telegraph code and system of transmission accordlng to which the energy consumed is, to a certain degree, proportional to the number of telegraphic units transmitted during a time unit. A further object of the invention is to render automatic, as far as possible, the whole process of disguising the message at the sending and of reconstituting it at the receiving station in order to avoid loss of time and manipulation errors.

The general principle of the invention is as follows By means of a device, consisting of a relay and two lamp-resistances connected in a certain way, through which device the impulses of the message pass simultaneously with impulses constituting a key-series, a certain number of signals at the beginning of the message are'altered, said arrangement pausing, whenever a message-impulse and a key-impulse coincide, the rupture of the circuit passing from the apparatus according to the invention through the armature of the relay mentioned to a sending relay, thus preventing the transmission of the coinciding impulses, whereas, no rupture being caused by impulses of the message alone or of the key alone, these will be transmitted.

An advantage of the present invention is that it does not necessitate the use of a special transmitting device and key tapes for the key series mentioned, as in known inventions with a similar object, from which it also diiiers as regards the mode of utilizing the key series.

By means of devices hereafter described it is made possible always to obtain a maximum of coincidences between the impulses of the message and those of the key. The key-impulses, however, serve to change only a relatively short, arbitrarily predetermined length of the message at its beginning,

whereafter the signals of the original message will automatically take the place of the key-signals, so that a certain length of a message with a following one is, generally speaking, obtained by registering the message on a cylindrical commutator from which the impulses are derived after a certain interval of time, said commutator being arranged so as to eliminate impulses falling on every second unit, thus reducing to a minimum the chances of coincidence between impulses and intervals according to the Morse code. The reduced and disguised message is transmitted as usual.

At the receiving station the signals are restored to their original form by means of a device consisting of a relay and two lampresistances, arranged exactly as the one already mentioned at the sending station,

through which device pass, at the beginning and during a certain part of the reception, impulses received through the antenna and further impulses pertaining to a key-series, but afterwards and throughout the message, impulses directly received and those previously received and registered by means of devices essentially the same and working in synchronism with those of the sending station. The initial synchronism is obtained by the aid of a transmission of special signals, and is automatically maintained and constantly corrected by a group of relays commanding electro-mechanical regulating devices.

In order to make fully comprehensible the following description and the. difference between the present invention and other devices for disguising telegrams, already known in the art, it is necessary in the first place to explain the combination of two series of impulses as realized according to the invention by means of the arrangement of a relay and two lamp-resistances.

The invention is illustrated in the accompanying drawings which will be more fully explained hereinafter.

In the drawings:

Fig. 1 is a representation of the application of the general principle of the invention to a series of Morse signals.

Fig. 2 is a diagrammatic representation of a relay device in accordance with the invention.

Fig. 3 is a further representation of the application of the principle of the invention to a series of Morse signals.

Fig. 4 is a diagrammatic representation of transmitting and receiving apparatus in accordance with the invention.

Fig. 5 is a vertical sectional view of a structural embodiment of the apparatus shown in Fig. 4.

Fig. 5 is a plan view and Fig. 5 is a view of a detail of the apparatus shown in Fig. 5. i

Fig. 6 is a diagrammatic representation of the effect of imperfect synchronization of the transmitting and receiving apparatus.

Fig. 7 is a representation of an arrangement of apparatus for correcting imperfect synchronization.

Supposing X, in diagram Fig. 1, to be a series of Morse signals, synchronized, as regards its telegraphic units, with a series of arbitrary signals Y, the series last mentioned being composed in such a manner that none of its impulses coincide with even units of X. then it will be seen that, if the principle of combination be, that two impulses in the series X and Y, when coinciding, cause an interval, but that an impulse only in the one or only in the other of these series causes an impulse in the resulting series Z, Z will always show fewer impulses than X, whatever be the composition of Y, as long as its impulses are distributed on odd units only.

Fig. 2 shows the arrangement and connections of the relay and the two lamp-resistances aforementioned. The relay coil R is connected 011 one side by the conductor 4 to the conductor 1, on the other side by the conductor 5 to the conductor 2, 1 and 2 being both united to conductor 3 and by the conductor 3 to one pole, for instance, to the negative pole of the source of current. Two lamps L and L of the same resistance, suitably chosen as compared to the resistance of the relay coils, are inserted in the conductors 1 and 2, L between conductors 3 and 4, L between 3 and 5.

If a positive impulse arrives by conductor 1, it will pass through lamp L and conductor 3 to the negative pole and also through conductor 4, the relay-coils, conductors 5 and 2 and lamp L to conductor 3 and said pole. Consequently the relay will be energized and attract its armature a against a contact-part a which is connected by a conductor 6 to the )ositive pole from which an impulse will pass through the armature a, connected by a conductor 7 to the sending relay. If a positive impulse arrives by conductor 2, the effect will of course be the same, but if both conductors 1 and 2 are simultaneously connected to the positive pole, the relay R will remain inactive, there being in that case no potential difference between conductors 4 and 5. Consequently, supposing the impulses of series X, in the diagram Fig. 1, to arrive by conductor 1, those of series Y by conductor 2, a suitable device, inserted between conductor 7 and the negative ole, may register the impulses of series Z. n the other hand it is evident that, if the impulses of series Z arrive by conductor 1, and those of series Y by conductor 2, the registering device will mark the reconstituted Morse series X, the rule of combination being reversible.

As already mentioned in the introduction, the series which in the demonstration relating to diagrams 1 and 2 represents the key-series is in reality composed of two distinctly diiferent parts, viz: at first of an arbitrarily chosen sequence of impulses and intervals of the nature already described and comprising an even number of units, and

afterwards of a derivation of a Morse series, in which derivation all impulses on even units are eliminated, as illustrated in Fig. 3, in which X represents the message to be communicated in Morse code, in this example the word Paris. Y is the initial and arbitrary key, in this example comprising 10 units, and Y represents the derivation of X in which, consequently, impulse units 11, 13 15 correspond to impulse units 1, 3, 5 of X respectively, whereas units 12, 14, 16 of Y intervals correspond to units 2, 4, 6 of X respectively; 2 and 6 being intervals, but 4 being an impulse.

The apparatus according to the invention is provided with a member materializing the initial key-series Y and also with a member for continuously registering the derivation Y of the message, Y being utilized for the composition of series Z, which is transmitted in such a way that the interval between corresponding units in series X and Y is always equal to the length of the initial keyseries Y The apparatus according to the invention, adapted to two stations for transmission and for reception of radiograms, is diagrammatically shown in Fig. 4. Parts which are identical in shape and function on the transmission-side (to the right of Fig. 4) to such on the reception side (to the left) are indicated by the same characters.

A, B, C and D represent the developed circumferences of circular discs, divided into an even number of alternately conducting and non-conducting segments, against which collecting or distributin brushes 6A, 6B, 6C and bD, respectively, ear. All the discs are of the same diameter. Discs B, C and D have the same number of segments. Half the circumference of disc A is of conducting, the other half of non-conducting material. As shown in the diagram the positions of the discs with respect to one another are such that all the collecting brushes .bA-bD, moving with the same speed and in the same direction round the discs, will come into contact with a conducting segment at the same moment. The conducting half of disc A is electrically connected to the positive pole of the source of current. As shown for one single segment, every conducting segment of disc B can be connected to the corresponding conductingsegment of disc C by means of key K. Each one of the segments last mentioned is connected to one end of the windings of a coil K1, the other end of which is connected to the negative pole. If the coil is energized, a cont-act Kc will be closed, one part of which is connected to the positive pole, the other toone of the conductmg segments of disc D. There are as many keys K, coils Kr and contacts Kc as there are conducting segments on each of the three discs last mentioned.

On the right hand side of the diagram, showing the arrangements for transmitting '1 indicates a common transmitter for Morse signals by means of a perforated strip, supposed to send positive impulses, 72 indicates a key with nine contact parts, -70 and Rt a relay coil.

As indicated in Fig. 4 the key is may be posed in two diflerent positions. The keyparts 70 k is and is are mechanically con nected but insulated from one another. Part 70 is electrically connected to the positive, part k to the negative pole. Part 70 is connected to the collecting brush 6A, part k to the transmitter contact 10, part is to one end of the windings of relay coil Rt, the other end of same being connected to a contactpart 12. When the coil Rt is not energized, said part 12 is in contact with another contact-spring 13, connected both to the distributing-brush 12C and to the key part A). The brush bB is connected to one part 11 of a contact, the other part of which, 11, is an armature of the coil Rt and connected to the positive pole. When the coil Rt is energized, contact 11*, 11 is interrupted. It will be seen that, if the key K is placed-as indicated for its parts k 7%, A2 70 by dotted lines, a positive impulse through the transmitter contact 10 will pass through keyparts la, is, these being then in contact, to the relay-spring 13. If coil Rt is not energized and contact 13, 12 consequently closed, the transmitter impulse will pass through the windings of the coil; and contact 70, k and to the negative pole. The relay coil Rt will be energized and interrupt the connection of the distributor brush bB with the positive pole by breaking the contact 11, 11', already mentioned. A. part 14 serving as armature to Rt will be attracted and, first closing the contact 14, 12, will break contact 13, 12. Part 14 is connected to the key part 71: in the supposed position making contact with k which is connected to the positive pole. I Thus, the coil Rt, being on one side connected to the negative pole through parts k, k, and on the other side to the positive pole through parts 12, 14, 70*, 70 will remain energized as long as the main current is not interrupted or the key is placed in the position shown by full lines. Besides the above-mentioned contact parts 11*, 11-, 12,

13, 14 the relay Rt is provided with four contact parts 15, 16, 17 and 18 of which 16 brush bD, and contact 18, 17, the part lastmentioned being connected to keypartlc in contact with In, which is connected to the negative pole. Between k and the negative pole a lamp-resistance L is inserted, [a and L being both connected to the coil R according to the scheme'described in the introduction and shown in the diagram Fig. 2. On the other side the coil R, connected over a lamp-resistance L to L and the negative pole, is also connected to the contact-part 15, of relay Rt; consequently a circuit may be established from the positive pole through the transmitter contact 10, keyparts is, is, relay contacts 16, 15, and lamp L to the negative pole.

The functioning of the relay R, depending upon the closing of one or the other or of both circuits just mentioned, has already been described with reference to Fig. 2.

To assure the synchronous working of the transmitter T relatively to the rotation of the brushes bA bD, the motor parts commanding both are mechanically connected in such a way that an impulse of one unit, sent by the transmitter, always corresponds to the course of a brush along one conducting segment of the discs B, G or D.

As already indicated, the arrangement of the discs, brushes and connections between these parts at the receiving station, as shown in the left side of Fig. 4, are identical to those described above for the transmitting station, this being also the case as regards the lamps L L and relay R on both sides.

Instead of the key 7c, the receiving apparatus is provided with a relay R1 with eontact parts 1926, 36, 37 and with another relay Rr which corresponds to the relay Rt on the transmitting side, contact parts 2731, and 32, 33 of R1 being identical as regards arrangement with 11 14 and 17, 18, respectively, of Rt. The connections be tween the two relays R7 and R7, between their contact parts and the brushes 72A and 251) on the receiving side are as follows:- Brush 6A is connected to part 21 which when relay R1 is inactive, is in contact with armature 20 connected to lamp L Brush 72B is connected to part 27, in contact with armature 28 when relay R1" is inactive, 28 being connected to the positive pole.

Parts 23 and 30, in contact with parts 22, and 29, respectively, when the relays are inactive, are connected together. Brush 6C is connected to armature 36 of relay R1. When attracted, .36 makes contact with part 37 connected to parts 23 and 30 aforementioned. An armature 24, belonging to relay Br and connected to the positive pole, when attracted, first makes contact with part 22 and then breaks contact 22, 23. Part 22 is connected on one side to armature 31, which, when attracted by relay-coil Rr first makes contact with part 29, and then breaks contact 29, 30. On the other side 22 15 connected to one end of the windings of the coils Rr, the other end being connected, by means of a hand-switch SLUI to the negative pole. WVhen relay R1 is energized, contact-part 20 already mentioned will close with part 19, connected to part 32 of relay Rr which part, when the latter relay is energized, will make contact with part 33, connected to collector brush bD. Between part 20 and lamp L is inserted a relay-coil Rs which, when energized, will close a contact 59, 60, part 60 being connected to the positive pole, and part 59 to a group of relays described further on and serving to maintain the synchronism between transmitting and receiving devices. This group of relays is also connected to a part 61 which makes contact with a part 62 when a relay-coil R8 is energized. Part 62 is connected to the positive pole. Coil R81 is inserted between lamp L and the relay of the antenna. The contacts aforementioned, 25, 26 and 20, 21, are adjusted so that 20, 21 will always be interrupted before 25, 26 is closed.

All the discs, A, B, O, D, form a cylindrical block, round which the brushes, bA, bB, b0, 5D are rotated by means of a motor driven device. Evidently the motors at both stations must be regulated to a sulficient degree of synchronism, and the position of the brushes relatively to the disc-block at both stations must correspond. The discs A serve to facilitate this.

Supposing the key 70 on the transmitting side to be initially in the position shown by full lines in Fig. 4, the brush-carrying device rotating at a certain speed, the contact of relay R will transmit a signal of a length corresponding to half the revolution of the brushes round the discs, with an interval between two signals of exactly the same length.

These signals being easily recognized at the receiving station, the operator on that side has to tune his driving device as nearly as possible to the same speed, an operation which is facilitated by the disposition of relay R and lamps L L between the contact 20, 21, and the antenna, seeing that a sequence of impulses of the same length as their intervals will also pass from the positive pole through disc A at the receiving station through contact 20, 21 to lamp 1), while the impulses of the same nature received pass through lamp L Consequently, if the motor devices at both stations have different speeds, the result in the relay R on the receiving side will be a period of signals, or of intervals, of gradually increaslngand decreasing length whereas a perfect timlng of the driving devices to the same speed will give signals and intervals of constant length. If also the positions of the brushes relatively to the conducting segments of discs A is the same at both stations, the impulses in question beginning and ceasing simultaneously, relay R at the receiving station will remain inactive, which will be the criterion of a perfect synchronization.

In order to permit of obtaining this result the disc block at the receiving station is adjustable and may be turned by hand into the required position.

An absolute synchronism, such as would result from the tuning of the driving devices on both sides to exactly the same constant speed, being however impossible to obtain by mechanical adjustment only, even if us ng accurate phonic motors regulated by pendulum vibrators, the practical result would only be a considerable extension of the period of gradually increasing and decreasing signals. In order to maintain the perfect synchronism existing at a certain moment the receiving device is provided with six relays and two electro-magnets, the coils of which are indicated on Fig. 4 by S S and Ma, Mr, respectively. The contacts and connections of those members are as follows S will, when'energized, close a contact 36, 37 otherwise interrupted. S will, when energized, close a contact 38, 39 and break a contact 40, 41 the former one bein otherwise interrupted, the latter one close As regards arrangement and functions coil S contacts 51, 50, coil S contacts 49, 48, and 47, 46 correspond exactly to coil S contacts 36, 37, coil S and contacts 38, 39 and 40, 41, respectively, and on the order mentioned.

When energized coil S will make two contacts 42, 43 and 44, 45 both otherwise interrupted; this will also be the case with coil S", contacts 52, 53 and 54, 55.

The contact-part 59 already mentioned as pertaining to relay R8 is connected by a conductor 58 to parts 37 and 40, as also to one end of the windings of coils S and S the other ends of these being connected by a conductor 57 to the switch 8W serving to connect to the negative pole. 57 is also connected to contact-parts 38, 45, 49, 52 and to one end the windings of coils S and S. The other ends of these are connected by a conductor .56 to the contact-part 61 already mentioned as pertaining to t e relay Rs 56 being also connected to parts 50,47. Coil S is inserted between parts 36 and 39. Parts 39 and 44 are connected to one end of the winding of electromagnet Ma, the other end of which winding is connected to part 43. Parts 41 and 42 are connected together. Coil S is inserted between parts 51 and 48. Parts 48 and 53 are connected to one end of the windings of electromagnet M1, the other end of which winding is connected to part 54. Parts 46 and 55 are connected together.

Supposing the switch Sw temporarily connected to the negative pole, it will be seen that, when contact 61, 62, is closed and contact 59, 60 interrupted, coils S and S will be energized. ThlS, however, w1ll not 1nfiuence coils S Ma, S or Mr, seeing that the connections of S and Ma to the ositive ole by way of contact 36, 37 and t ose of S and Mr to the negative pole by way of contact 48, 49 are interrupted. If contact 59, 60 is closed, and contact 61, 62 interrupted, coils S and S alone will be energized, the case being invertedly analogous to the one just explained, and regarding S, Ma, S and M1 the result will be the same.

But supposing contact 61, 62, first to be closed and to remain so when, subsequently, contact 59, 60 is closed, the case will be different. As before, S and S? will at once he energized when closing contact 61, 62, S then interrupting contact 40, 41, making contact 38, 39 and connecting S to the negative pole by conductor 57. On the subsequent closing of contact 59, 60 coils S and S will be energized, and S will close contact 36, 37, thus connecting S to the positive pole by conductor 58. S will then make the contact 44, 45 and thereby connect itself and also Ma permanently to conductor 57 and the negative pole, at the same time closing contact 42, 43. But S having previously interrupted contact 40, 41, the circuit of magnet Mm will remain interru ted, except if contact 61, 62 is then interrup ed, in which case S will cease to be energized, and contact 40, 41 will be closed. S remaining energized and keeping contact 42, 43, closed, Ma will become connected to the positive pole by contacts 42, 43 and 40, 41, conductor 58 and contact 59, 60, and remain energized as long as the contact last mentioned remains closed. On the contrary the excitation of coils S and S will have no effect on magnet M1, seeing that, though S is energized contact 46, 47 remains interrupted as long as S is energized on account of contact 59, 60 being closed, consequently M1 will not be connected to the positive pole.

Supposing the case to be inverted, viz, contact 59, 60 first to be closed and then contact 61- 62 the latter one remaining so after 59, 60 has been interrupted, Mr will be energized and remain so as long as contact 61, 62 remains closed. First S and S will be energized, S interrupting contact 46, 47 and closing contact 48, 49, thus connecting S and Mr to the negative pole by conductor 57. But S will be energized only when S becomes so on account of the subsequent closing of contact 61, '62. S will then close the contact 52, 53 and thereby connect itself. and also Mr-permanently to conductor 57 and the negative pole, at the same time closing contact 54, 55. But Sthaving previously interrupted contact-46, 47 the circult of ma net Mr will remain interrupted, except 1f contact 59, 60 is then interrupted, in which case S will cease to be energized, and contact 46 47 will be closed. S remaining energized and keeping contact 54, 55 closed, Mr will become connected to the positive pole by contacts 54, 55 and 46, 47, conductor 56 and contact 61, 62 and remain energized as long as the contact last mentionedremains closed. On the contrary the excitation of coils S and S will have no effect on magnet Ma, seeing that, though S is energized, contact 40, 41 remains interrupted as long as S is energized on account of contact 61, 62 being closed, consequently Ma will not be connected to the positive pole.

If both contacts 59, 60 and 61, 62 are simultaneously closed and interrupted, it is easy to see that neither Ma nor M1 can be excited, contacts 40, 41 and 46, 47 being interrupted all the While coils S and S are energized.

The closing of contacts '59, 60 and 61, 62 depending upon the energizing of coils R8 and B8 respectively, that is, upon the impulses arriving to lamps L and L respectively, it will be easily understood that, ac cording to the above, neither of the coils Ma and Mr will be energized if a perfect synchronism exists between impulses from both stations, but that, as soon as the impulses arriving through the antenna to the relay R on the receiving side by way of the lamp L are in advance, magnet Ma will be energized during the time the impulse by Way of coils Rs persists after the ceasing of the impulse through the antenna, consequently during a space of time proportional to the error in synchronism. This will of course also be the case with M1" during the time an impulse from the transmittin side persists after the ceasing of the impu se on the receiving side by way .of coils Rs. Magnet Ma thus being active proportionally to the advance of the transmitting device, magnet Mr proportionally to the advance of the receiving one, the former magnet may be used for accelerating, the latter one for retarding the receiving device, so as to maintain the synchronism, in the manner later described. shows 4 a vertical section through the principal parts of the apparatus.

-In the bottom plate 101 the vertical shaft 102 is fixed in the'centre of an insulating disc 103 which is also fixed to the bottom plate. On the shaft is pivoted a disc 104, provided with a toothed ring 105, gearing with a pinion 106 fixed on a shaft 107 which, by means of an adjustable friction gear 108, 109, serving to regulate the speed, receives a rotary motion from the motor shaft 110 (Fi 5 To the rotating disc 104 is also fixed a vertical arm 111 east in one piece with 'the pivot bearing 112 of said disc. Above sai 113 is placed, cast in one piece with a vertical arm 114 which, by means of a stop-pin 115 (Fig. 5") may be adjusted to one of several positions determined by holes 116 at a given distance from one another around the disc 104. On the insulating disc 103 six metal rings 117, 118, 119, 120, 121 and 122 are concentrically fixed, insulated from one another and from the bottom plate. On the under side of the disc 104 is fixed a piece of insulating material 123, which carries six metal springs 124 to 129 placed tangentially to and pressing against the aforesaid rings 117122.

The vertical shaft 102 also carries a cylindrical block consisting of'five discs 130, 131, 132, 133 and 134, kept together by bolts 137 and fixed by means of bolts 138 to a centre piece 135 which, by means of a nut 136, screwed on the upper end of the shaft 102, may be fixed to the shaft. The disc 130 is made of insulating material and carries round its circumference a number of contact segments 139, 140, arranged in two horizontal circles, so that each piece 139 is "situated exactly above one piece 140, but

insulated therefrom. The disc 130 with its contact-pieces just mentioned corresponds to the discs B and O on Fig. 4.

Separated from 130 b the insulating disc 131 another disc 132 is ept in place by the bolts 137. Half the circumference of disc 132, which corresponds to disc A on Fig. 4 is made of insulating, the other half of conducting material. Underneath said disc another such disc 133 is situated made of insulating material and carrying round its circumference contact-pieces 141, located exactly underneath pieces 139, 140. The disc 133 corresponds to the disc D in Fig. 4. The bottom disc 134 of the blo'ckgis of metal and carries a circular contact ring 142 insulated from the disc.

An insulating piece 143 fixed to the rotating arm 111 carries five metal springs 144148 serving as collector brushes and pressing against the contact-pieces 139, 140, disc 132, disc 134 and ring 142. An insulating piece 149, fixed to the vertical arm 114, carries a spring-collector brush 150 pressing bearing another such bearing nected according to the scheme shown in Fig. 4, electric impulses may be transmitted through the conducting parts of discs 130- 134 as described with reference to discs A, B, O and D in Fig. 4. The key K serving to effect the connection between conducting parts of discs B and C (Fig. 4) 'is in reality, as shown by Fig. 5, a metal pin 161 passing through contact-piece'139 and disc 130, the

lower end of which pin may be screwed into a hold 160 in contact-piece 140. When this is not done, a coil spring 162 between piece 139 and a knob 163 of insulating material,

fixed to the upper end of the spring, keeps it in the position shown in Fig. 5 so that the connection between the contact-piece 139 and 140 is interrupted. There is one such pin 161 for each pair of contact-parts. just mentioned. The knob 163, passes through a hole in a circular disc 1 52 fixed by bolt 137 and distance tubes 151 at a suitable distance above disc 130. In order to give access to the fastening-nut 136, disc 152 has a central aperture 153. The coils K0 shown in Fig. 4 as connected by one end of their windings to conducting parts of O are in reality as shown in Fig. 5, solenoids 154 fixed with their upper ends to the disc 152 and descending through corresponding holes in discs 130-133 to the lower surface of the disc last mentioned, which is situate at a small distance from the corresponding parts of the disc 134 in order to permit the movable armature 155 of each solenoid, when not attracted, to rest on disc 134. Pivoted on a bolt 157 screwed through disc 133 into-the metal part of disc 132 is a horizontally movable lever 156 of conducting material kept by the spring 156 in such a position, as shown by full lines in Fig. 5, as to press with one end against the armature 155, when this is not attracted. One end of the windings of the solenoid 154 is electrically connected to one of the contact-pieces 139, the other end being connected to the ring 142 by means of an insulated conductor passing through a hole 159 in disc 134. When the armature 155 is lifted by the energized solenoid, the inner end of lever 156 will pass underneath the armature and its opposite end will, by the action of coil-spring 156, press against the pin 158, fixed in the contact-segment 141, which will thus be electrically connected to discs 132 and 134, said parts 155, 156, and 158 corresponding to the contact K0 in Fig. 4.

One of each of the parts 154-l58 is provided for each contact-segment 141.

iii

windings of therelay coil R, lamp L and The vertical arm 111 carries an insulated protruding piece 164 the endof which, as shown in Fig. 5, will abut against the outwardly extending end of such levers 156 as have been drawn into contacts with the pins 158, and thus interrupt said contacts and replace the levers in their former position.

In order to realize, conformably to what has been mentioned with reference to the diagram, Fig. 4, the different impulses through the conducting parts above described with reference to Fig. 5, the collector ring 117, (Fig. 5) is connected to the negative pole of the source of current, collector ring 122 to the positive pole; the connections of the other collector rings being such as to correspond, that of 119 to that of brush bA (Fig. 4) that of 120 to that 'of brush bB (Fig. 4), that of 121 to that of brush M) (Fig. 4) and that of 118 to that of brush bD (Fig. 4).

When using the apparatus now described, it is first necessary to arrange the sending and the receiving apparatus so as to be identical as regards the initial key, materially reproduced by means of the connection pins 161 Fig. 5, an arbitrary number of which are screwed down so as to connect their contact segments 139 and 140 with one another. It is to be observed that the adjustments of the pins must be identical at both stations not only in themselves but also in respect to disc 132, said discs corresponding as already mentioned, to those designated by A on Fig. 4.

The following operation will serve the purpose of synchronizing the driving devices on both sides. The key K is placed as shown by full lines in Fig. 4 and the motor on the transmission side is started. Signals of a length equal to their intervals will then be regularly emitted by means of disc A, the local circuit being: positive pole, disc A, brush bA, contacts 3 and 2 of the key is,

negative pole. The relay R activating its sending contact, these signals will be transmitted through the antenna to the receiving side on which the starting of the motor will cause a similar emission of synchronizing signals through disc A, and contact 21, 20, the switch Sw being interrupted. Lamp L on the receiving side being connected to the antenna and lamp L on the same side to the disc A, it is evident that a perfect synchronization, both as regards motor speed and also as regards phase of discs A that is, of the whole central block of the apparatus on both sides, respectively, to the rotating parts, will result in neutralization of the signals by one another, so that relay R on the receiving side will not work. A registering device, for instance, a recording drum, worked by means of the contact of relay R on the receiving side would then give a straight line without signals. Supposing thls result to be obtained, the transmission of the message may immediately follow. During the synchronization period impulses passing from the positive pole through contacts 11 11 on the transmitting side and 27, 28 on the receiving one, respectively, will energize such coils K! as are connected to keys K (161 in Fig. 5) adjusted for connection between discs 13 and C (conducting segments 139, 140 in Fig. 5).

Consequently the corresponding contacts Kc (156 158 Fig. 5) will be closed, in other words, the impulses in question will successively be registered on the conducting segments of discs D by connecting the corresponding segments to the positive pole, but these connections will not be utilized during the synchronization, contacts 17, 18 on the transmitting and 32, 33 on the receiving side respectively, being then interrupted. When starting the transmission, the key is is placed in the position shown by dotted lines on Fig. 4 and the transmitter T is started. lVhen the first signal passes from the positive pole through the transmitter contact 10, keyparts IN, 7:, relay-contacts 13, 12, coil Rt, key-parts 7e", is", to the negative pole, the coil Rt will be energized and close contacts 17, 18, and 12, 14 while interrupting 12, 13, thus permanently establishing the connec-' tion to the positive pole over key-parts is, 10 and permitting the impulses, registered on disc D as mentioned above, to pass by contact 18, 17 and key-parts k 72 to the combining relay R. Simultaneously with these impulses those passing to the other side of the relay R from the positive pole through the transmitter-contact 10, key-parts A15, and relay-contacts 16, 15, which have also been closed at the first transmitter impulse, will be combined with the impulses passing through the conducting segments of discs. D,

and, as described in the introduction, the result will be a series of denatured and reduced signals transmitted by means of the contact of relay R. During the first part of the transmission the original transmitter impulses, i. e., Morse signals, will be combined with impulses passing by the conducting segments of disc D corresponding to the arbitrary connections between discs B and C by means of the keys K. The length of this seriesof initial key impulses is determined by the circumferential distance between the brush-carrying parts 111 and 114 (Fig. 5*). As soon as the corresponding angle of rotation has been traversed by said parts, the transmitter impulses from contact 10, conveyed by key-parts 76 is" to the distributing brush 6C and disc C, will by means of the intermediate parts Kr and K0, be registered on discs D and will take the place of the initial key impulses, which is easily understood,

mitter impulse, then immediately interrupts contacts 11, l1, and that no impulses can thereafter pass through the conducting parts of disc 8,. Moreover, the interrupting arm 164 shown on Fig. 5" which precedes the brush 144 (Fi 5) correspondmg to brush 60 (Fig. 4), W111 render it impossible to utilize an impulse registered on disc D more than once, so that the initial key-impulses registered on conducting segments 141 of disc 133 Fig. 5), between brushes 144 and 150, once aving been collected by the brush last-1nentioned, new transmitter impulses will successively be registered and collected, serving as aforesaid, to influence relay R (Fig. 4) or to neutralize simultaneous transmitter impulses arriving at the opposite end of the windings of said relay. It is supposed that the arbitrary connections, representing the initial key are identical in transmitting and receiving devices. As soon as the synchronization is attained on the receiving side (to the left in Fig. 4) the switch SW is placed so as to connect to the negative pole. As has been explained with reference to Figs. 1 and 2, the series of signals resulting from the combination of the denatured signals received through the antenna with the initial key impulses must be automatically decoded so as to become identical with those of the original message passing through the transmltter at the sending station. The first impulse from the positive pole through the armature of relay R on the receiving side will follow immediately when the synchronizing signals from the transmitting side cease on account of the key is having been placed so as to interrupt the contact between its parts 2 and 3, and it will pass through contact 22,23 and relay coil R1 to the negative pole, energizing the coil and closing contact 25, 26 at the same time establishing a permanent connection 22, 24 to the positive pole and thus maintaining coil R1 energized. The next impulse through the contact of relay R on the receiving side will then correspond to the first transmitter impulse sent and it will pass through the contact 30, 29, the relay coil R7,

which will be energized and through contact 25, 26, just established to the negative pole. The relay R? will be maintained energized through the establishing of'contact 29, 31 connected to the positive pole through contact 22, 24. The effect of the working of both relays will be :first the interruption of the contact 20, 21, causing synchronization disc A to be disconnected, so'that no more synchronizing signals will arrive at relay R, secondly the closing of contact 36, 37 connecting the contact of relay R to the brush of disc C. This disc will receive impulses exactly corresponding to those of the line message, impulses that will be registered on disc D. A third effect will be the establishing of contacts 32, 33, and 19,20, which will The whole procedure on the receiving'side I will thus evidently be the exact reversal of that on the transmitting side and consequently a registering device connected to and receivin its impulses through the contact of relay iR of the receiving device will record the same signals as sent by the transmitter T at the sending station.

Referring tothe diagram Fig. 3, which gives an example of denaturation, it, will be seen that, when reconstructing series X through the combination of series Y and Z realized as just described by means of the receiving device certain impulses in series Z, received through the antenna, coincide with impulses of the same length in series Y which, according to the above description are registered on and utilized by means of disc D. On account of the special construction of discs B, C and D, both in the sending and receiving device, every second segment of said discs being made of insulating material, it can never happen that the impulses in question in series Y and Z will beof greater length than one telegraphic unit. It is this peculiarity which is utilized for the maintenance of the synchronism during transmission and reception by means of the relays Rs, Rs, S -S and the electromagnets Ma and Mr, already described (Fig. 4). If the synchronism of the apparatus on both sides is imperfect, one of the two Cases I, II, shown in diagram Fig. 6 will occur, as regards such isolated impulses in series Y and Z as ought correctly to begin and end exactly at the same moment.

In both cases Y represents an impulse from disc D, and Z an impulse received through the antenna. In Case I, the receiving apparatus, in Case II, the transmitting apparatus is in advance. Consequently and conformable to the preceding description of the correcting device, the clectro-magnet Mr (Figs. 4 and 7) will be energized in Case I during a time corresponding to the space E, Fig. 6, and electro-magnet Ma, during the same time in Case II.

Figs. 7 shows, schematically, one form of mechanical arrangement for utilizing the action of these magnets so as to correct the momentary position of the collecting-brushes relatively to the disc-block.

On the outward end of the gear-shaft 107, Figs. 5 and 7, a brake disc 165 is fixed. Against the circumference of this disc a member 166 serving as a friction brake and fixed on an iron lever 168, is normally pressed by the action of a coil spring 170,

acting on the lever which is pivotally mounted on an axle 173. .The action of spring 170 can be'regulated by the counteraction of another' coil spring 172 which is adjustable. Lever 168' serves-as armature to the magnet Ma, and will, when attracted by the magnet, liberate disc 165 from the braking influence of member 166, thus causing the acceleration of the revolving parts 165, 107", 106 and of the brush-carrying device. driven by the gear 105,106, (Fig, 5). The magnet Mr is provided with a similar brake arrangement 167, 169, 171, 174, which how, ever, differs from that just described in this that the member 167 is normally kept out of action by the coil spring 171, but pressed against disc 165 by the attraction of magnet Mr. The brake and the magnet in question are calculated so as momentarily to arrest the rotation of disc 165 and shaft 107, when the-magnet is energized; the friction gear 108, 109, Fig. 5 will then slip.

I claim: 1. In an apparatus for transmltting and for receiving telegraphic messages 1n Morse code, means for disguising the message and reducing the number and length of impulses in the series of signals transmitted as compared With the series of Morse signals and for reconstituting the series of Morse signals through the combined efiect of two series, each composed of impulses separated by intervals, said means including a relay, said relay comprising a contact, an electromagnet and two lamp-resistances, said three members last mentioned being connected in a closed circuit, said circuit, between the lamps, being connected to one pole of a source of current and, between each lamp and the electro-magnet, to a conductor for the impulses of one of the series to be combined, the contact commanded by the electromagnet being connected so as to close and to interrupt a circuitfor transmitting or for recording of signals. 1

21- Inan apparatus for transmitting and for receiving telegraphic messages in Morse, means for disguising the message and reducing the number and length of impulses in the series of signals transmitted as compared with the series of Morse signals and for reconstituting. the series of Morse signals through the combined effect of two series, each composed of impulses separated by intervals, said means including a combining relay, means for composing and registering different series of impulses of constant length separated by arbitrary intervals, said means comprising a key disc, a registering disc and a collecting disc, said discs having the same number of alternating conducting and non-conducting segments of the same circumferential extent, arbitrarily arrangeable connections between corresponding segments of the key disc and the registering disc, electromagnets, one for-each conducting segment of said registering disc, the electromagnets being connected on one side to said last mentioned segments andon the other side to one pole of a source of current, one contact for and commanded by each registering magnet and connected on one sideto the otherpole of a source of current and on'the other side to one conducting segment of the collecting disc, a distributin brush for the key disc, a collecting brus for the collecting disc, said brushes being arranged so as to come successively and simultaneously into contact with corresponding segments of their discs and temporarily connect the distributing brush to the same pole: as the contact and the collecting brush for the third disc to one side of the electromagnet of the combining relay. 7

3. In an apparatus for transmitting and for receiving telegraphic messages in Morse f code, means for disgulsing the message and reducing the number and length of impulses in the series of signals transmitted as .compared with the series of Morse signals and for reconstituting the series of Morse signals through the combined effect of two series, each composed of impulses separated by intervals, said means including a combining relay, means for utilizing any predetermined number of impulses of an ini-,

tial key-series, said means comprising'a revolving member, two members each carrying a brush fixed thereto in an arbitrarily variable relative position, arelay arranged and connected so as to close its own circuit as soon as energized and'then to interrupt the connection of one brush to one pole and to connect the other brush to one side of the electro-magnet of the combining relay.

4:. In an apparatus for transmitting and for receiving telegraphic messages in Morse code, means for disguising the message and reducing the number and length of impulses in the series of signals transmitted as compared with the series of Morse signals and for reconstituting the series of Morse sig nals through the combined effect of two.

series, each composed of impulses separated a by intervals, said means including a combining relay, means for registering and utilizing a series of impulses of constant length separated by intervals depending upon the composition of a series of Morse si als, said means comprising a registering iso and a collecting disc, said disc's having the same number of alternatingly conducting and non-conducting segments of the same circumferential extent, electro-magnets one for each conducting segment of the registering disc connected on one side to said segment and on the other side to one pole of a source of current, one contact for and commanded by each electro-magnet and connected on one side of the pole opposite to that already -mentioned and on the otherside to one conducting segment of the collecting disc, a distributing brush for the registering disc connected to the electromagnet and a collecting brush for the collecting disc, the brushes being arranged so as to come simultaneouslyinto contact with corresponding successive segments and temporarily connect the first-mentioned brushon the transmitting side to the contact of a transmitter for Morse signals and on the receiving side to the contact of the combining rela and the second mentioned brush to one slde of the electro-magnet of the combining relay.

5. In an apparatus for transmittlng and for receiving telegraphic messages in Morse code, means for disguisin the message and reducing the number and ength of impulses in the series of signals transmitted as comared with the series of Morse signals, and or reconstituting the series of Morse signals through the combined effect of two series, each com osed of impulses Separated by intervals, sai means including a combining relay, means for utilizin an redetermined number of impulses of an initial key-,

series, said means comprising a revolving member, two members each carrying a brush fixed thereto in an arbitrarily variable relative position, a relay arranged and connected so as to closeits own circuit as soon as energized and then to interrupt the connection of one brush to one ole and to connect the other brush to one si e of the electro-magnet of the combining relay, means for preventing utilization of any part of a key-series more than once, comprising devices each composed of a movable armature of a registering magnet, each armature being arranged to influence a lever connected to one pole of the source of current and establishing, when the armature is attracted, a connection between said pole and a part of a conductin segment of the collecting disc and an e ectrically insulated member fixed to a revolving member carrying the distributing brushes, said insulated member being arranged so as, before the brushes come *into contact with the corresponding segments, to influence successively, each lever forming contact, thereby interrupting the contact and replacing the lever in a position in which it may be again influenced by the armature.

6. In an apparatus for transmitting and for receiving telegraphic messages in Morse code, means for disguisin the message and reducing the number and length of impulses in the series of signals transmitted as compared with the series of Morse signals and for reconstituting the series of Morse signals through the combined effect of two series, each composed of impulses separated by intervals, said means including a combining relay, means for composin and registering different series of impulses of constant length separated by arbitrary intervals, said means comprising a key disc, a registering disc and a collectln disc,- said discs having the same number 0 alternating conducting and nonconducting segments of the same circumferential extent, arbitrarily arrangeable connections between corresponding segments of the key disc and the registering disc, registering electromagnets one for each conducting segment of said registering disc, the electromagnets being connected on one side to said last mentioned segments and on the other side to one pole of a source of current, one contact for and commanded by each registering magnet and connected on one side to the other pole or a source of current and on the other side to one conducting segment of the collecting disc, a distributing brush for the key disc, a collecting brush for the collecting disc, said brushes being arranged so as to come successively and simultaneously into contact with corresponding segments of their discs and temporarily connect the distributing brush to the same pole as the contact and the collecting brush for the third disc to one side of the electro-magnet of the combinin relay, means for indicating the degree 0 synchronism between transmittin and receiving devices by the aid of signa s emitted on both sides, signals which, when the receiving device is connected for reception and working synchronously with the transmittingdevice, are automatically interrupted at the receiving side on the receipt of an impulse from the line, and atthe sending side by the first impulse of the message transmitted, said means comprising on both sides identically arranged synchronization discs with conducting and non-conducing segments, immovably fixed relatively to the key, registering and collecting discs and having their conducting se ents connected to one pole of the source 0 current, collecting brushes for the synchronization discs, a switch on the transmitting side for connecting the brush to one side of the electromagnet of the combining relay, a switch on the receiving side for connecting the other pole of the source of current to one side of a relay, which, being arranged so as to close its own circuit as soon as energized, then interrupts a contact connecting it on one side to the contact of the combining relay. 7. In an apparatus for transmitting and for receiving telegraphic messages in Morse code, means for disguising the message and reducing the number and length of impulses in the series of signals transmitted as compared with the series of Morse signals, and for reconstituting the series of Morse signals through the combined effect of two series, each composed of impulses separated by intervals, said means including a combining relay, means for composing and registering difi'erent series of impulses of constant length separated by arbitrary intervals, said means comprising a key disc, a registering disc and a collecting disc, said discs having the same number of alternating conducting and non-conducting segments of the same circumferential extent, arbitrarily arrangeable connections between corresponding segments of the key disc and the registering dlsc, registering electromagnets one for each conducting segment of said registering disc, the electromagnets being connected on one side to said last mentioned segments and on the other side to one pole of a source of current, one contact for and commanded by each registering magnet and connected on one side to the other pole of a source of current and on the other side to one conducting segment of the collecting disc, a distributing brush for the key disc, a collecting brush for the collecting disc, said brushes being arranged so as to come successively and simultaneously into contactwith corresponding segments .of their discs and temporarily connect the distributing brush to the same pole as the contact and the collecting brush for the third disc to one side of the electro-magnet of the combining relay, means for ensuring automatically the simultaneous functioning of corresponding members for composing, registering and utilizing the difi 'erentseries on both sides, said means comprising on the receiving sidetwo relays, the one connected to and commanded by the contact of the combining relay and arranged so as to close its own circuit when energized and then to connect the collecting brush of the registering disc to the contact of the combining relay, one pole of the source of current to one side of the other relay which, on the other side is temporarily connected to the contact of the combining relay and arranged so as, when energized, to close its own circuit, at the same time interrupting the temporary connection last mentioned and the connection between one pole and the distributing brush of the keydisc, and connecting the collecting-brush of the collecting disc over a contact already closed by the first mentioned relay to one side of the electro-magnet'of the combining relay.

8. In an apparatus for transmitting and for receiving telegraphic messages in Morse code, means for disguising the message and reducing the number and length of impulses in the series of signals transmitted as compared with the series of Morse signals, and for reconstituting the series of Morse signals through the combined eflect of two series, each composed of impulses separated by intervals, said means including a combining relay, means for energizing members serving to maintain and correctthe synchronism between transmitting and receiving devices alternately in accordance with the sense of errors in synchronism and proportionally to the degree of error, said means comprising,

relay then closing a contact connecting two relays one in each group on one side to one pole of the source of current, these four relays being on the other side connected over an interrupter to the other pole, and so arranged and connected, that the first relay of each group connects when energized, the third relay of the same group on one side to a contact-part of the corresponding repeating relay, said third relay of each group being on the other side connected to one side of the corresponding electro-magnet and to a contact-part of the second relay of the same group, this relay being arranged so as to connect, when energized, its contact part mentioned'to the interrupter and to interrupt a connection between the contact of the in question is not connected, and a contactpart commanded by the third relay of the same group so as to be connected to the side not mentioned ofthe corresponding electromagnet, the third relay being arranged so as to connect, when energized, itself and the corresponding electro-magnet to the interrupter. v

I 9. In an apparatus for transmitting and for receiving telegraphic messages in Morse code, means for disguising the message and reducing the number and length of impulses in the series of signals transmitted as compared with the series of Morse signals, and for reconstituting the series of Morse signals through the combined effect of two series, each composed of impulses separated by intervals, said means including a combin ing relay, means for utilizing any predetermined number of impulses of an initial key-series, said means comprising a revolving member, two members each carrying a brush fixed thereto in an arbitrarily variable relative position, a relay arranged and connected so as to close its own circuit as soon as energized and then to interrupt the connection of one brush to one pole and to connect the other brush to one side of the electromagnet of the combining relay, means for utilizing the alternative energizing of two electromagnets for correction in both senses tion of said disc, the one continuously, exof the speed of the revolving members, said cept when one of the electro-magnets is means comprising, on the receiving side, a energized, and the other oneonl when the 10 gear driven through an intermediate friction other electro-magnet'is ener 'ze gear, the driven part of which is fixed on In testimony whereof I ave signed my the same axle as a circular disc, and two name to this specification.

members mechanically. influencing the rota- ARVID GERHARD DAMM. 

